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FliZ is a posttranslational activator of FlhD4C 2-dependent flagellar gene expression

Lookup NU author(s): Dr Jonathan Brown, Dr Phillip AldridgeORCiD


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Flagellar assembly proceeds in a sequential manner, beginning at the base and concluding with the filament. A critical aspect of assembly is that gene expression is coupled to assembly. When cells transition from a nonflagellated to a flagellated state, gene expression is sequential, reflecting the manner in which the flagellum is made. A key mechanism for establishing this temporal hierarchy is the σ28-FlgM checkpoint, which couples the expression of late flagellar (Pclass3) genes to the completion of the hook-basal body. In this work, we investigated the role of FliZ in coupling middle flagellar (Pclass2) gene expression to assembly in Salmonella enterica serovar Typhimurium. We demonstrate that FliZ is an FlhD 4C2-dependent activator of Pclass2/middle gene expression. Our results suggest that FliZ regulates the concentration of FlhD4C2 posttranslationally. We also demonstrate that FliZ functions independently of the flagellum-specific sigma factor σ28 and the filament-cap chaperone/FlhD4C 2 inhibitor FliT. Furthermore, we show that the previously described ability of σ28 to activate Pclass2/middle gene expression is, in fact, due to FliZ, as both are expressed from the same overlapping Pclass2 and Pclass3 promoters at the fliAZY locus. We conclude by discussing the role of FliZ regulation with respect to flagellar biosynthesis based on our characterization of gene expression and FliZ's role in swimming and swarming motility. Copyright © 2008, American Society for Microbiology. All Rights Reserved.

Publication metadata

Author(s): Saini S, Brown JD, Aldridge PD, Rao CV

Publication type: Article

Publication status: Published

Journal: Journal of Bacteriology

Year: 2008

Volume: 190

Issue: 14

Pages: 4979-4988

ISSN (print): 0021-9193

ISSN (electronic): 1098-5530

Publisher: American Society for Microbiology


DOI: 10.1128/JB.01996-07

PubMed id: 18469103


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